The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A198481 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A198481

Square root of the largest square dividing ((2n-1)!)^(2n-3).
(history; published version)

#13 by Harvey P. Dale at Fri May 24 18:59:59 EDT 2024

STATUS

editing

approved

#12 by Harvey P. Dale at Fri May 24 18:59:56 EDT 2024

MATHEMATICA

Sqrt[#]&/@Table[Max[Select[Divisors[((2n-1)!)^(2n-3)], IntegerQ[Sqrt[#]]&]], {n, 7}] (* Harvey P. Dale, May 24 2024 *)

STATUS

approved

editing

#11 by Jon E. Schoenfield at Sun Aug 09 15:59:38 EDT 2015

STATUS

editing

approved

#10 by Jon E. Schoenfield at Sun Aug 09 15:59:37 EDT 2015

CROSSREFS

Cf. A134367, A197880.

#9 by Jon E. Schoenfield at Sun Aug 09 15:59:29 EDT 2015

COMMENTS

For the complementary square free squarefree parts see A197880.

FORMULA

a(n) = A000188(A134367(2*n-1)). - _R. J. Mathar, _, Oct 25 2011

MAPLE

seq(A198481(n), n=1..10) ; # _R. J. Mathar, _, Oct 25 2011

STATUS

approved

editing

#8 by Russ Cox at Sat Mar 31 10:22:18 EDT 2012

AUTHOR

_Artur Jasinski (grafix(AT)csl.pl), _, Oct 25 2011

Discussion

Sat Mar 31

10:22

OEIS Server: https://oeis.org/edit/global/339

#7 by T. D. Noe at Tue Oct 25 21:08:55 EDT 2011

STATUS

reviewed

approved

#6 by R. J. Mathar at Tue Oct 25 17:27:11 EDT 2011

STATUS

proposed

reviewed

#5 by R. J. Mathar at Tue Oct 25 16:35:09 EDT 2011

STATUS

editing

proposed

#4 by R. J. Mathar at Tue Oct 25 16:34:53 EDT 2011

NAME

Square parts of (n!)^(n - 2)

Square root of the largest square dividing ((2n-1)!)^(2n-3).

COMMENTS

For the complementary square free parts see A197880.

FORMULA

a(n) = A000188(A134367(2*n-1)). - R. J. Mathar, Oct 25 2011

MAPLE

A000188 := proc(n)

a := 1 ;

for pf in ifactors(n)[2] do

p := op(1, pf) ;

e := op(2, pf) ;

a := a*p^(floor(e/2)) ;

end do:

a ;

end proc:

A198481 := proc(n)

A000188( A134367(2*n-1)) ;

end proc:

seq(A198481(n), n=1..10) ; # R. J. Mathar, Oct 25 2011

CROSSREFS

Cf. A134367, A197880

STATUS

proposed

editing